Phenyl-Substituted Thiaboranes─Linked 2D and 3D Aromatics as Noncovalent Organic Framework Materials

A series of 12-phenyl-closo-thiaboranes (12-(4-X-C₆H₄)-closo-1-SB₁₁H₁₀, where X = OMe (2), X = SMe (3), X = Ph (4), and X = NMe₂ (5)) has been prepared. Except for 2, all compounds exhibit a chalcogen bond of thiaborane to the phenyl ring or the neighboring molecule as major supramolecular structural motif. 5, having the strongest (-12.47 kcal/mol) structure-making intermolecular interaction via noncovalent S···π(phenyl) chalcogen bond, was crystallized from different solvents in the form of various solvatopolymorphs. n-Hexane and diethyl ether can be removed from 5 easily upon the formation of a porous material with large cavities (up to 20.5% of the unit cell). This first stable and useful noncovalently bound organic framework material with an ultramicroporous structure exhibits a molecular sieve effect. The selective and repeatable adsorption of CO₂ to the material crystallized from n-hexane was explained on the basis of cooperative and consecutive machine-like molecular interactions of quadrupolar CO₂ molecule with B-H and amino groups inside rectangular cavities.